Cutter drive assembly for biopsy device

Abstract

A biopsy device comprises a body, a needle, and a cutter actuation mechanism. The needle extends distally from the body. The cutter actuation mechanism rotates and translates the cutter relative to the body and relative to the needle. The cutter has an overmold presenting a lead screw and a hex portion. The cutter actuation mechanism comprises a first gear disposed about the hex portion of the overmold and a second gear engaged with the lead screw of the overmold by a nut that is integral with the second gear. The cutter actuation mechanism is operable to simultaneously rotate the first gear relative to the body at a first rotational speed and the second gear relative to the body at a second rotational speed. With the lead screw and the nut rotating at different rotational speeds, the lead screw rotates relative to the nut at a third rotational speed.

What is claimed is: 
     
       1. A biopsy device, comprising:
 (a) a body; 
 (b) a needle extending distally from the body; 
 (c) a cutter configured for translation relative to the needle; 
 (d) a first rotating member disposed within the body; 
 (e) a second rotating member disposed within the body; and 
 (f) a drive assembly disposed within the body and operable to simultaneously rotate the first and second rotating members; 
 wherein the first and second rotating members each comprise a gear, wherein one gear of the first or second rotating member is larger than another gear of the first or second rotating member, wherein the differently sized gears are configured to cause the first and second rotating members to rotate at different rotational speeds when the first and second rotating members receive a single rotational input; 
 wherein the first rotating member and the second rotating member are rotatable about a common axis; 
 wherein the difference in rotational speeds of the first and second rotating members with both first and second members rotating is configured to provide translation of the cutter relative to the needle. 
 
     
     
       2. The biopsy device of  claim 1 , wherein the cutter is configured to rotate relative to the needle. 
     
     
       3. The biopsy device of  claim 2  wherein the rotational speed of the cutter is the same as the rotational speed of one of the first or second rotating members. 
     
     
       4. The biopsy device of  claim 2  wherein one of the first or second rotating members is configured to rotate at the same rotational speed as that of the cutter, and the other of the first or second rotating members is configured to rotate at a rotational speed less than the rotational speed of the cutter. 
     
     
       5. The biopsy device of  claim 1  wherein the drive assembly comprises a motor operable to drive rotation of one or both of the first or second rotating members. 
     
     
       6. The biopsy device of  claim 5  wherein the motor comprises an electric motor. 
     
     
       7. The biopsy device of  claim 1  wherein the body comprises a handpiece sized and shaped to be held and manipulated by a single hand. 
     
     
       8. The biopsy device of  claim 1  wherein the drive assembly comprises a single motor operable to drive rotation of the first and second rotating members in the same direction at different rotational speeds. 
     
     
       9. The biopsy device of  claim 1  further comprising a tissue sample holder disposed proximally of the cutter to receive tissue samples severed by the cutter and transported through the cutter, and wherein at least one of the first and second rotating members is disposed around the cutter and rotates relative to the cutter. 
     
     
       10. A biopsy device, comprising:
 (a) a needle; 
 (b) a cutter configured for translation relative to the needle; 
 (c) a nut; 
 (d) a screw; and 
 (e) a drive assembly, wherein the drive assembly comprises a first gear and a second gear, wherein the first gear is in communication with the nut, wherein the second gear is in communication with the screw, wherein the first gear and second gear have different pitch diameters, wherein the difference in pitch diameter is operable to simultaneously drive the nut and screw at different rotational speeds; 
 wherein engagement of the nut and screw at the different rotational speeds is operable to translate the cutter relative to the needle. 
 
     
     
       11. The biopsy device of  claim 10  wherein cutter is configured for rotation relative to the needle. 
     
     
       12. The biopsy device of  claim 11  wherein the cutter and one of the screw and the nut rotate at the same speed. 
     
     
       13. The biopsy device of  claim 10  wherein the nut is disposed around the cutter and rotates relative to the cutter. 
     
     
       14. The biopsy device of  claim 10  wherein the nut is driven at a rotational speed less than the rotational speed of the screw. 
     
     
       15. The biopsy device of  claim 10  wherein the drive assembly is operable to drive the nut and screw out of engagement with each other. 
     
     
       16. The biopsy device of  claim 15  wherein the drive assembly is operable to drive the nut and screw into engagement with each other. 
     
     
       17. The biopsy device of  claim 10  wherein the drive assembly is operable to rotate the nut and screw in a first rotational direction to advance the cutter, and wherein the drive assembly is operable to rotate the nut and screw in an opposite rotational direction to retract the cutter. 
     
     
       18. A hand held biopsy device comprising:
 (a) a handpiece sized and shaped to be held and manipulated by a single hand of user; 
 (b) a needle extending distally from the handpiece; 
 (c) a cutter translatable with respect to the needle to sever tissue; 
 (d) a tissue sample holder disposed at a proximal end of the handpiece for receiving tissue samples severed by the cutter; 
 (e) a vacuum pump disposed within the handpiece, the vacuum pump operable to provide vacuum for transporting tissue samples severed by the cutter to the tissue sample holder along a tissue sample transport path; 
 first and second rotatable members disposed for rotation about the tissue sample transport path, wherein the first and second rotatable members are in communication with a first and second gear respectively, wherein the first and second gear have different pitch diameters; and 
 (g) a battery operated motor disposed within the handpiece; 
 wherein the motor is operable to drive the vacuum pump; 
 wherein the motor is operable to drive the first and second rotatable members at different rotational speeds via the first and second gears to provide translation of the cutter relative to the needle. 
 
     
     
       19. The biopsy device of  claim 18  wherein the tissue sample transport path extends through the cutter. 
     
     
       20. The biopsy device of  claim 18  wherein the second rotatable member comprises an internally threaded member, wherein the first rotatable member comprises an externally threaded member, the internally threaded member and the externally threaded member configured to be driven at different rotational speeds, and the internally threaded member and the externally threaded member being engageable one with the other along a direction generally parallel to the tissue sample transport path, wherein engagement of the internally threaded member with the externally threaded member provides is configured to provide translation of the cutter.